A pilot uses flight instruments and associated displays to navigate an aircraft. The easier it is for the pilot to obtain and understand the information provided by these instruments and displays, the more likely that the pilot will be able to successfully navigate the aircraft. This is especially true during approach and landing on a runway.
Currently, instrument landing systems (ILS), microwave landing systems (MLS), or satellite landing systems (SLS) are used to guide aircraft during landing. These systems typically use a deviation bar on a horizontal indicator to indicate lateral deviation from the approach course and a glide scope indicator to indicate vertical deviation from the glide scope. The deviation bar and the glide scope indicator provide flight path deviation information to the pilot, allowing the pilot to make flight path corrections while landing.
Because looking at the horizontal indicator causes the pilot to look away from the cockpit window, some aircraft have incorporated a head-up display. The head-up display projects symbology representing the deviation bar and glide scope indicator onto a screen integrated into the cockpit window, so that the pilot can simultaneously view both the symbology and conditions outside the cockpit. This solution improves safety because the pilot can continue to monitor the situational progress of the flight while obtaining flight data. In addition, pilot fatigue is reduced by reducing the number of instruments needing to be scanned.
Initially, the symbology used on the head-up display to represent the information previously provided by the horizontal indicator was not intuitive. The pilot had to be trained to understand what data the symbology represented and how to interpret the data. By making the symbology more intuitive, aircraft navigation is simplified, pilot error and fatigue is reduced, and safety is increased.
An improvement to symbology format is addressed in U.S. Pat. No. 5,745,863 titled “Three Dimensional Lateral Displacement Display Symbology Which Is Conformal To The Earth,” which is assigned to the same assignee as the present invention and is hereby incorporated by reference in its entirety. U.S. Pat. No. 5,745,863 describes using two-dimensional lines to depict an extended course centerline, which extends towards a vanishing point near a horizon line on the display, and two-dimensional deviation marks on either side of an aircraft symbol.
While U.S. Pat. No. 5,745,863 describes some improvements regarding display symbology, additional improvements can be made. These additional improvements may further simplify aircraft navigation, reduce pilot error and fatigue, and increase safety.